• Udakarahada Sutta

There are four kinds of sheets of water:

• (1) Flat (uttāna) but deep in appearance (obhāsa);

• (2) deep but flat in appearance;

• (3) flat and flat in appearance;

• (4) deep and deep in appearance.

So, also, there are four classes of people:

• handsome in appearance but shallow in mind;

• not handsome in appearance but deep in knowledge;

• neither handsome nor wise;

• both handsome and wise (A.ii.105-6).